Question

Carlos gas tank is 1/10 full. After he buys 11 gallons of gas, it is 3/5 full. How many gallons can carlos tank hold?

Answer 1

Current amount of gas: $\frac{1}{10} t$                    

After adding 11 gallons: $\frac{1}{10} t$   + 11  = $\frac{3}{5} t$  

11 = $\frac{3}{5} t$   - $\frac{1}{10} t$

11 = $\frac{6}{10} t$   - $\frac{1}{10} t$

11 = $\frac{5}{10} t$

11 = $\frac{1}{2} t$

22 = t

Answer:  22 gallons